#!/usr/bin/node

const log = console.log,
      arg = process.argv[2];

if(typeof(arg) === undefined ||
    arg === '--help'||
    arg === '--h'){
      help();
    }
else{
  calc();
}

function help(){
  const msg = ''
    + 'usage: cmd-name [OPTION][expression]\n'
    + 'evaluate the expression.\n'
    + '\n'
    + "Mondatory arguments to long options are mandatory for short options too.\n"
    + '  -h,-help output help information and exit\n';
  log(msg);
}

function calc(){
  log(arg + '=%s' , eval(arg));
}
